In other words, PHP is a loosely-typed language, so a string is often just as good as an integer and vice versa. Example:
$a = '0032';
$b = $a + 32;
echo "Result is: $b"; // Result is: 64
If you don't like that answer, then consider this: 32 is the same as 032 which is the same as 0032 which is the same as... etc. The difference between '32' and '032' would only be observed in the displaying of that number (e.g. outputting a string). To that end, if you want to display a number left-padded with zeros, consider using [man]printf/man (or one of its numerous relatives). Example:
$a = '0032';
$b = $a + 32;
printf("Result is: %04d", $b); // Result is: 0064